A335 P9 Pipe MAWP Calculator ASTM A335 -P9 Alloy Steel Pipe SMLS 9Cr-1Mo
Material Properties Description
ASTM A335 -P9 Alloy Steel Pipe SMLS 9Cr-1Mo
Min Design Temperature
-20 °F
Y Coefficient
Ref 3 — Ferritic steels
Maximum Allowable Working Pressure (psig) Sch STD Sch XS Sch 160
NPS OD (in) 100 °F 200 °F 300 °F 400 °F 500 °F 600 °F 700 °F 800 °F 1/8 0.405 6,659 6,027 5,794 5,727 5,694 5,594 5,427 5,128 1/4 0.54 6,438 5,827 5,601 5,537 5,505 5,408 5,247 4,957 3/8 0.675 5,210 4,715 4,533 4,481 4,455 4,377 4,246 4,012 1/2 0.84 4,995 4,521 4,346 4,296 4,271 4,196 4,071 3,846 3/4 1.05 4,074 3,687 3,544 3,503 3,483 3,422 3,320 3,137 1 1.315 3,810 3,448 3,314 3,276 3,257 3,200 3,105 2,933 1 1/4 1.66 3,137 2,839 2,729 2,698 2,682 2,635 2,557 2,415 1 1/2 1.9 2,822 2,554 2,455 2,427 2,413 2,370 2,300 2,173 2 2.375 2,377 2,152 2,068 2,045 2,033 1,997 1,938 1,831 2 1/2 2.875 2,600 2,353 2,262 2,236 2,223 2,184 2,119 2,002 3 3.5 2,258 2,043 1,964 1,941 1,930 1,896 1,840 1,738 3.5 4 2,059 1,863 1,791 1,771 1,760 1,730 1,678 1,585 4 4.5 1,914 1,732 1,665 1,646 1,636 1,608 1,560 1,474 5 5.563 1,678 1,518 1,460 1,443 1,434 1,409 1,367 1,292 6 6.625 1,524 1,380 1,326 1,311 1,303 1,280 1,242 1,174 7 7.625 1,421 1,286 1,236 1,222 1,215 1,194 1,158 1,094 8 8.625 1,342 1,214 1,167 1,154 1,147 1,127 1,094 1,033 9 9.625 1,275 1,154 1,110 1,097 1,090 1,071 1,039 982 10 10.75 1,217 1,102 1,059 1,047 1,041 1,023 992 937 12 12.75 1,051 951 914 904 899 883 857 809 14 14 955 865 831 822 817 803 779 736 16 16 834 755 726 717 713 701 680 642 18 18 740 670 644 636 633 622 603 570 20 20 665 602 579 572 569 559 542 512 22 22 604 546 525 519 516 507 492 465 24 24 553 500 481 476 473 464 451 426 26 26 510 462 444 439 436 428 416 393 28 28 473 428 412 407 405 397 386 364 30 30 441 399 384 380 377 371 360 340 36 36 367 332 320 316 314 308 299 283 42 42 314 285 274 270 269 264 256 242 44 44 300 272 261 258 257 252 245 231 46 46 287 260 250 247 245 241 234 221 48 48 275 249 239 236 235 231 224 212
Allowable Stress vs Temperature 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 1000 1100 1200 Temperature (°F) 0 5 10 15 20 Allowable Stress (ksi) Disclaimer: This calculator is for guidance only. Results are based on ASME B31.3-2024 allowable stresses for seamless pipe (Ej=1.0, W=1.0). Always verify against the current edition of the standard. The engineer of record is responsible for all design decisions.
References ASME B31.3-2024 — Process Piping, Table A-1 ASME B36.10M — Welded and Seamless Wrought Steel Pipe ASME B16.5-2020 — Pipe Flanges and Flanged Fittings 
